pathcopies: give up any optimization based on `introrev`
Between
8a0136f69027 and
d98fb3f42f33, we sped up the search for the
introduction revision during path copies. However, further checking show that
finding the introduction revision is still expensive and that we are better off
without it. So we simply drop it and only rely on the linkrev optimisation.
I ran `perfpathcopies` on 6989 pair of revision in the pypy
repository (`hg perfhelper-pathcopies`. The result is massively in favor of
dropping this condition. The result of the copy tracing are unchanged.
Attempt to use a smaller changes preserving linkrev usage were unsuccessful, it
can return wrong result. The following changesets broke test-mv-cp-st-diff.t
- if not f.isintroducedafter(limit):
+ if limit >= 0 and f.linkrev() < limit:
return None
Here are various numbers (before this changeset/after this changesets)
source destination before after saved-time ratio
worth cases
e66f24650daf 695dfb0f493b 1.062843 1.246369 -0.183526 1.172675
c979853a3b6a 8d60fe293e79 1.036985 1.196414 -0.159429 1.153743
22349fa2fc33 fbb1c9fd86c0 0.879926 1.038682 -0.158756 1.180420
682b98f3e672 a4878080a536 0.909952 1.063801 -0.153849 1.169074
5adabc9b9848 920958a93997 0.993622 1.147452 -0.153830 1.154817
worse 1%
dbfbfcf077e9 aea8f2fd3593 1.016595 1.082999 -0.066404 1.065320
worse 5%
c95f1ced15f2 7d29d5e39734 0.453694 0.471156 -0.017462 1.038488
worse 10%
3e144ed1d5b7 2aef0e942480 0.035140 0.037535 -0.002395 1.068156
worse 25%
321fc60db035 801748ba582a 0.009267 0.009325 -0.000058 1.006259
median
2088ce763fc2 e6991321d78b 0.000665 0.000651 0.000014 0.978947
best 25%
915631a97de6 385b31354be6 0.040743 0.040363 0.000380 0.990673
best 10%
ad495c36a765 19c10384d3e7 0.431658 0.411490 0.020168 0.953278
best 5%
d13ae7d283ae 813c99f810ac 1.141404 1.075346 0.066058 0.942126
best 1%
81593cb4a496 99ae11866969 1.833297 0.063823 1.769474 0.034813
best cases
c3b14617fbd7 743a0fcaa4eb 1101.811740 2.735970 1099.075770 0.002483
c3b14617fbd7 9ba6ab77fd29 1116.753953 2.800729 1113.953224 0.002508
058b99d6e81f 57e249b7a3ea 1246.128485 3.042762 1243.085723 0.002442
9a8c361aab49 0354a250d371 1253.111894 3.085796 1250.026098 0.002463
442dbbc53c68 3ec1002a818c 1261.786294 3.138607 1258.647687 0.002487
As one can see, the average case is not really impacted. However, the worth case
we get after this changeset are much better than the one we had before it. We
have 30 pairs where improvements are above 10 minutes.
This reflect in the combined time for all pairs
before: 26256s
after: 1300s (-95%)
If we remove these pathological 30 cases, we still see a significant improvements:
before: 1631s
after: 1245s (-24%)
revlog.parseindex must be able to parse the index file even if
an index entry is split between two 64k blocks. The ideal test
would be to create an index file with inline data where
64k < size < 64k + 64 (64k is the size of the read buffer, 64 is
the size of an index entry) and with an index entry starting right
before the 64k block boundary, and try to read it.
We approximate that by reducing the read buffer to 1 byte.
$ hg init a
$ cd a
$ echo abc > foo
$ hg add foo
$ hg commit -m 'add foo'
$ echo >> foo
$ hg commit -m 'change foo'
$ hg log -r 0:
changeset: 0:7c31755bf9b5
user: test
date: Thu Jan 01 00:00:00 1970 +0000
summary: add foo
changeset: 1:26333235a41c
tag: tip
user: test
date: Thu Jan 01 00:00:00 1970 +0000
summary: change foo
$ cat >> test.py << EOF
> from __future__ import print_function
> from mercurial import changelog, node, pycompat, vfs
>
> class singlebyteread(object):
> def __init__(self, real):
> self.real = real
>
> def read(self, size=-1):
> if size == 65536:
> size = 1
> return self.real.read(size)
>
> def __getattr__(self, key):
> return getattr(self.real, key)
>
> def __enter__(self):
> self.real.__enter__()
> return self
>
> def __exit__(self, *args, **kwargs):
> return self.real.__exit__(*args, **kwargs)
>
> def opener(*args):
> o = vfs.vfs(*args)
> def wrapper(*a, **kwargs):
> f = o(*a, **kwargs)
> return singlebyteread(f)
> wrapper.options = o.options
> return wrapper
>
> cl = changelog.changelog(opener(b'.hg/store'))
> print(len(cl), 'revisions:')
> for r in cl:
> print(pycompat.sysstr(node.short(cl.node(r))))
> EOF
$ "$PYTHON" test.py
2 revisions:
7c31755bf9b5
26333235a41c
$ cd ..
#if no-pure
Test SEGV caused by bad revision passed to reachableroots() (issue4775):
$ cd a
$ "$PYTHON" <<EOF
> from __future__ import print_function
> from mercurial import changelog, vfs
> cl = changelog.changelog(vfs.vfs(b'.hg/store'))
> print('good heads:')
> for head in [0, len(cl) - 1, -1]:
> print('%s: %r' % (head, cl.reachableroots(0, [head], [0])))
> print('bad heads:')
> for head in [len(cl), 10000, -2, -10000, None]:
> print('%s:' % head, end=' ')
> try:
> cl.reachableroots(0, [head], [0])
> print('uncaught buffer overflow?')
> except (IndexError, TypeError) as inst:
> print(inst)
> print('good roots:')
> for root in [0, len(cl) - 1, -1]:
> print('%s: %r' % (root, cl.reachableroots(root, [len(cl) - 1], [root])))
> print('out-of-range roots are ignored:')
> for root in [len(cl), 10000, -2, -10000]:
> print('%s: %r' % (root, cl.reachableroots(root, [len(cl) - 1], [root])))
> print('bad roots:')
> for root in [None]:
> print('%s:' % root, end=' ')
> try:
> cl.reachableroots(root, [len(cl) - 1], [root])
> print('uncaught error?')
> except TypeError as inst:
> print(inst)
> EOF
good heads:
0: [0]
1: [0]
-1: []
bad heads:
2: head out of range
10000: head out of range
-2: head out of range
-10000: head out of range
None: an integer is required( .got type NoneType.)? (re)
good roots:
0: [0]
1: [1]
-1: [-1]
out-of-range roots are ignored:
2: []
10000: []
-2: []
-10000: []
bad roots:
None: an integer is required( .got type NoneType.)? (re)
$ cd ..
Test corrupted p1/p2 fields that could cause SEGV at parsers.c:
$ mkdir invalidparent
$ cd invalidparent
$ hg clone --pull -q --config phases.publish=False ../a limit --config format.sparse-revlog=no
$ hg clone --pull -q --config phases.publish=False ../a neglimit --config format.sparse-revlog=no
$ hg clone --pull -q --config phases.publish=False ../a segv --config format.sparse-revlog=no
$ rm -R limit/.hg/cache neglimit/.hg/cache segv/.hg/cache
$ "$PYTHON" <<EOF
> data = open("limit/.hg/store/00changelog.i", "rb").read()
> poisons = [
> (b'limit', b'\0\0\0\x02'),
> (b'neglimit', b'\xff\xff\xff\xfe'),
> (b'segv', b'\0\x01\0\0'),
> ]
> for n, p in poisons:
> # corrupt p1 at rev0 and p2 at rev1
> d = data[:24] + p + data[28:127 + 28] + p + data[127 + 32:]
> open(n + b"/.hg/store/00changelog.i", "wb").write(d)
> EOF
$ hg -R limit debugrevlogindex -f1 -c
rev flag size link p1 p2 nodeid
0 0000 62 0 2 -1 7c31755bf9b5
1 0000 65 1 0 2 26333235a41c
$ hg -R limit debugdeltachain -c
rev chain# chainlen prev delta size rawsize chainsize ratio lindist extradist extraratio
0 1 1 -1 base 63 62 63 1.01613 63 0 0.00000
1 2 1 -1 base 66 65 66 1.01538 66 0 0.00000
$ hg -R neglimit debugrevlogindex -f1 -c
rev flag size link p1 p2 nodeid
0 0000 62 0 -2 -1 7c31755bf9b5
1 0000 65 1 0 -2 26333235a41c
$ hg -R segv debugrevlogindex -f1 -c
rev flag size link p1 p2 nodeid
0 0000 62 0 65536 -1 7c31755bf9b5
1 0000 65 1 0 65536 26333235a41c
$ hg -R segv debugdeltachain -c
rev chain# chainlen prev delta size rawsize chainsize ratio lindist extradist extraratio
0 1 1 -1 base 63 62 63 1.01613 63 0 0.00000
1 2 1 -1 base 66 65 66 1.01538 66 0 0.00000
$ cat <<EOF > test.py
> from __future__ import print_function
> import sys
> from mercurial import changelog, pycompat, vfs
> cl = changelog.changelog(vfs.vfs(pycompat.fsencode(sys.argv[1])))
> n0, n1 = cl.node(0), cl.node(1)
> ops = [
> ('reachableroots',
> lambda: cl.index.reachableroots2(0, [1], [0], False)),
> ('compute_phases_map_sets', lambda: cl.computephases([[0], []])),
> ('index_headrevs', lambda: cl.headrevs()),
> ('find_gca_candidates', lambda: cl.commonancestorsheads(n0, n1)),
> ('find_deepest', lambda: cl.ancestor(n0, n1)),
> ]
> for l, f in ops:
> print(l + ':', end=' ')
> try:
> f()
> print('uncaught buffer overflow?')
> except ValueError as inst:
> print(inst)
> EOF
$ "$PYTHON" test.py limit/.hg/store
reachableroots: parent out of range
compute_phases_map_sets: parent out of range
index_headrevs: parent out of range
find_gca_candidates: parent out of range
find_deepest: parent out of range
$ "$PYTHON" test.py neglimit/.hg/store
reachableroots: parent out of range
compute_phases_map_sets: parent out of range
index_headrevs: parent out of range
find_gca_candidates: parent out of range
find_deepest: parent out of range
$ "$PYTHON" test.py segv/.hg/store
reachableroots: parent out of range
compute_phases_map_sets: parent out of range
index_headrevs: parent out of range
find_gca_candidates: parent out of range
find_deepest: parent out of range
$ cd ..
#endif